Search PubMed⌕ Search

Biomedical subjects

E H Jansen

Publications and source records attributed to E H Jansen.

At least 37 records · Page 2Linked to original sources
PubMed1989

Fast detection of homogeneous chemiluminescent immunoassays with a sensitive photoplate.

Chemiluminescent immunoassays performed in microtitre plates can be detected with a sensitive instant photoplate. An apparatus was constructed for this purpose making use of whole polystyrene microtitre plates plates possible. One of the advantages of immunoassays using enzyme-enhanced chemiluminescence is the possibility for developing homogeneous immunoassays. An example is described for a solid-phase immunoassay for 17 beta-testosterone making use of non-specific energy transfer in combination with photoplate detection. A testosterone-peroxidase conjugate was used as label. Quantification was performed using image-analysis techniques. The assay was also performed with colorimetric substrates for comparison.

Immunoassay↗
PubMed1989

Characteristics and detection principles of a new enzyme label producing a long-term chemiluminescent signal.

A new enzyme label system is described which is superior to all existing chemiluminescence labels used in immunoassays. The system consists of the enzyme xanthine oxidase with hypoxanthine as substrate. The signal reagent contains perborate, an Fe-EDTA complex and luminol. The enzyme preparation and the signal reagent are very stable upon storage. The main features of the system are a long duration of the chemiluminescent signal (half-life time of 30 hours) and a very low limit of detection (about 3 amol). Possibilities and implications for the use of various measuring systems are discussed.

Half-Life↗
PubMed1989

Plasma proteins in growing analbuminaemic rats fed on a diet of low-protein content.

1. Analbuminaemic and Sprague-Dawley (control) rats were fed on low- (60 g/kg) protein and control (200 g protein/kg) diets ad lib. from weaning. Males and females were studied separately. Body-weight and plasma protein concentrations were determined at 10 d intervals from 25 to 75 d of age. Electrophoresis of plasma proteins was performed in samples from day 75. Extracellular fluid volume was measured at 10 d intervals from day 45 onwards. Colloid osmotic pressure was measured in plasma and interstitial fluid (wick technique) at the start and end of the trial. 2. Body-weight increased much less on the low-protein diet than on the normal diet in both strains and sexes. The growth retardation was slightly more pronounced in the male analbuminaemic rats than in the male Sprague-Dawley controls. 3. Plasma protein concentration increased during normal growth in all groups, particularly in the female analbuminaemic rats. This increase was reduced by the 60 g protein/kg diet in all groups, with the exception of the male analbuminaemic rats. 4. Differences in plasma colloid osmotic pressure were similar to those seen in plasma protein concentration. Interstitial colloid osmotic pressure was higher in the control rats than in the analbuminaemic ones. The interstitial colloid osmotic pressure increased during growth in the control but not in the analbuminaemic rats. The difference in interstitial colloid osmotic pressure between the strains was maintained during low-protein intake, but at a lower level than during normal protein intake. 5. Subtracting interstitial from plasma colloid osmotic pressure, resulted in a rather similar transcapillary oncotic gradient in the various groups at 75 d, both on the control protein diet (11-14 mmHg), and on the low-protein diet (9-11 mmHg). 6. All protein fractions were reduced to a similar extent by the low-protein diet in the control rats, whereas in the analbuminaemic rats protein fractions produced in the liver were more severely depressed. 7. Extracellular fluid volume as a percentage of body-weight was similar in all groups, and decreased with increasing age. 8. In conclusion, the analbuminaemic rats were able to maintain the transcapillary oncotic gradient on both diets by reducing the interstitial colloid osmotic pressure. Oedema was not observed. 9. Despite the absence of albumin, the protein-malnourished analbuminaemic rat is no more susceptible to hypoproteinaemia and oedema than its normal counterpart.

Aging↗
PubMed1989

Application of diethylstilbestrol dipropionate in bulls. I. Excretion of residues in urine and faeces and histological and immunohistochemical changes in the prostate.

In this experiment 20 one year old bulls received a single intramuscular injection of the anabolic preparation diethylstilbestrol dipropionate (DES-DP) (an oil preparation or an emulsion). Four animals received a corresponding placebo. The application of DES-DP to bulls caused characteristic histological alterations in the peripheral glandular epithelium of the prostate, which could be observed until four weeks after treatment. The value of histological investigation as a screening method was, however, limited by the occurrence of only few metaplastic lesions and a rapid recovery. By contrast, immunohistochemistry using a polyclonal cytokeratin antiserum K40 appeared to be a specific and very sensitive method to detect oestrogen-induced lesions in the prostate. In only two animals, six weeks after injection with the DES-emulsion, false-negative results were obtained, demonstrating the potential value of this screening method. The excretion of DES in the urine and faeces was monitored using radioimmunoassay following chromatographic purification of the urine and faeces extracts. The excretion of DES in urine was faster for animals of the oil group. The DES content in urine decreased to the 1 microgram/l level after 42 days (emulsion group) or 70 days (oil group). The excretion in faeces was comparable to that in urine. After day 21 the excretion patterns of the two excreta were indistinguishable.

Animals↗
PubMed1989

Application of diethylstilbestrol dipropionate in bulls. II. Residues in bile, liver, kidney, muscle tissues and application site.

The second part of an experiment is described in which 20 one year old bulls were injected with diethylstilbestrol (DES) dipropionate containing preparations. Analysis of DES content was performed in several tissues, such as the injection site, diaphragm muscle, psoas muscle, liver, kidney and bile. In the injection site appreciable amounts of DES were found. Measurable amounts of DES were also found in liver and kidney until 4 weeks after injection. In bile, DES concentrations were even higher than those in urine, and were well correlated with DES concentrations in urine. Implications for screening purposes are discussed.

Animals↗
PubMed1986

Quantitative determination of diethylstilboestrol in bovine urine with isotope dilution mass spectrometry.

A method has been described for the quantification of diethylstilboestrol (DES) in bovine urine. The determining step is based on isotope dilution mass spectrometry (IDMS). The chemical work-up consisted of enzymatic deconjugation, Sep-Pak clean-up and high-performance liquid chromatography (HPLC). The labelled compound synthesized for IDMS is hexadeutero DES (DES-2H6). The labelled compound is not only used to quantify DES, but also to check the recovery of the chemical work-up procedure, in order to avoid false negative results. At the 1-5 micrograms l-1 level of urinary DES, the average recovery of 2 micrograms l-1 DES-2H6 is 70 +/- 20% (s.d.).

Animals↗
PubMed1986

A chemiluminescent immunoassay for zeranol and its metabolites.

A sensitive immunoassay is presented for the detection of the xenobiotic oestrogenic growth promotor zeranol (Ralgro) and the mycotoxin zearalanone. The detection is based on chemiluminescence using a zeranol-isoluminol conjugate. A lowest detectable amount of 2-5 pg zeranol per tube was achieved. The bovine zeranol metabolites zearalanone and taleranol can also be determined, and this has been shown in a metabolic pilot study of zeranol in veal calves. This study indicates that taleranol is a major metabolite in male veal calves, in contrast to zearalanone which is known to be the major metabolite in adult cattle.

Animals↗
PubMed1985

[A quarter of a century of studies of the abuse of hormonal anabolics in slaughtering animals: no DES-illusion!].

Over twenty-five years of analytical chemical and analytical biological forensic examination for residues of anabolic agents are reviewed. Up to 1981, this review is not only representative of the research done at the National Institute of Public Health but also of any research in this field in The Netherlands. A more detailed background is presented of the situation and the model of investigation adopted in the analytical-chemical testing of bovine urine for diethylstilbestrol (DES) following legal verdicts in 1981. At the time, examination in accordance with the Meat Regulations as well as a particular method of analysis were condemned. A retrospective study showed the rejected radioimmunochemical method (RIA) to be reliable as regards false-positive results at a level of 2 micrograms or more of DES per litre of urine (2 parts per billion or 2 ppb) rather than the level of 1 ppb adopted in 1981. Extensive and large-scale screening for DES from 1984 up to the present day resulted in the almost complete disappearance of the illegal use of this anabolic compounds in the Netherlands. However, investigations of sites of injection detected in slaughtered cattle during the period from 1983 to 1984, showed that other anabolics were still being used illegally. These studies particularly revealed residues of combined anabolic compounds ('cocktails'). The most common active anabolic ingredients observed were the xenobiotic steroids nortestosterone (nandrolone) and medroxyprogesterone and the exogenous natural steroids oestradiol and testosterone.

Anabolic Agents↗
PubMed1985

[Anabolic steroid residues in administration sites in slaughtering cattle. October 1983 - January 1985].

Samples from 573 sites of injection or implantation in carcasses of slaughtered cattle and veal calves in the Netherlands were studied by high performance liquid chromatography associated with on-line detection of the total UV spectrum (diode array detector). Anabolic substances were identified in 462 (100%) out of 573 samples. Nortestosterone was most frequently detected (84%) during the period from October 1983 to January 1985. Other xenobiotic steroids observed were medroxyprogesterone (14%), methyltestosterone (2%) and trenbolone (2%). The 'natural' steroids testosterone, oestradiol and progesterone were found in 29%, 66% and 3% of the samples respectively. The stilbene derivatives diethylstilboestrol (DES), dienestrol and hexoestrol were found in 2%, 3% and 0% of the samples. After re-introduction of DES control in the urine of cattle early in 1984, DES residues were no longer detected in the samples from sites of administration. Zeranol was not observed at all. If applicable, all anabolic agents were found to be present in a variety of esterified dosage forms.

Anabolic Agents↗
PubMed1985

Effective control for diethylstilbestrol in cattle in the Netherlands.

In the period from August 1981 to April 1983, 10243 random samples of urine from slaughtered cattle were inspected for the presence of the stilbene derivatives diethylstilbestrol (DES), dienestrol (DE), and hexestrol (HEX). Fast screening of all samples was performed by radioimmunoassay (RIA) with prior clean-up column chromatography. In this screening, 216 samples were indicated for confirmatory analyses by combined high performance liquid chromatography-gas chromatography-mass spectrometry (HPLC-GCMS) on account of an immunochemical response equivalent to 1 microgram/1 DES or more. The presence of DES was confirmed in 184 samples, DE in 5 samples and HEX in 14 samples. In the remaining 13 samples no stilbene derivative could be confirmed. From the results in 1984, after the introduction of the Meat Inspection Act, it is concluded that the use of stilbene derivatives in cattle in the Netherlands has dropped almost to zero. Of 4558 samples investigated, only 6 (0.13%) were indicated as 'stilbene' positive. The presence of DES was confirmed in 2 samples and DE in 4 samples.

Animals↗
PubMed1985

A specific radioimmunoassay for the detection of 19-nortestosterone in urine.

The antisera used were raised in rabbits against a 19-nortestosterone-7 alpha-carboxyethylthioether conjugate of bovine serum albumin. Tritium-labeled nortestosterone was used as tracer. Cross reactivities with metabolites of nandrolone, other anabolics and endogenous steroids were very low. To achieve additional specificity a clean up and separation procedure was developed, using isocratic high performance liquid chromatography. So far no qualitative discrepancies have been observed between the assay described here and confirmative determinations by combined high performance liquid chromatography-gas chromatography-mass spectrometry.

Animals↗